.Natural gas is often informally referred to as simply gas, especially when compared to other energy sources such as oil or coal.^While measuring by volume is useful, natural gas can also be measured as a source of energy.

Sources

Fossil natural gas

.In the 1800s, natural gas was usually produced as a byproduct of producing oil, since the small, light gas carbon chains come out of solution as it undergoes pressure reduction from the reservoir to the surface, similar to uncapping a bottle of soda pop where the carbon dioxide effervesces.^Where does natural gas come from?

.In the 1800s and early 1900s, such unwanted gas was usually burned off at the wellsite.^A gas flare stack is a common method used by producers and refiners for burning off unwanted natural gas or gas liquids.

.Often, unwanted gas (or 'stranded' gas without a market) is pumped back into the reservoir with an 'injection' well for disposal or repressurizing the producing formation.^Whether you're a producer, pipeline, local distribution company, marketer or end-user, NGW will keep you well-informed on every aspect of the North American natural gas scene.

^The Ministry of Petroleum & Natural Gas is entrusted with the responsibility of exploration and production of oil and natural gas, their refining, distribution and marketing,import, export, and conservation of petroleum products and Liquified Natural Gas.

[1]Gas-to-liquid, .(GTL) is a developing technology that converts stranded natural gas into synthetic gasoline, diesel or jet fuel through the Fischer-Tropsch process developed in World War II Germany.^Natural gas - the 'cleanest' of the fossil fuels .

^Natural Gas Storage is Critical Natural gas, a clean-burning fuel that provides a quarter of U.S. energy needs, is produced throughout North America and transported through a network of thousands of miles of pipelines.

^Educating fleet operators, State and National Transportation Safety directors, clean vehicle advocates and air quality and transportation policy-makers about the benefits of alternative fuel vehicles through seminars, media, and national conventions and expositions.

.Most major international oil companies are in advanced development stages of GTL production, with a world-scale (140,000 bbl/day) GTL plant in Qatar scheduled to come online before 2010. In locations such as the United States with a high natural gas demand, pipelines are constructed to take the gas from the wellsite to the end consumer.^Natural gas powers their plants and refineries.

.It sometimes contains significant quantities of ethane, propane, butane, and pentane—heavier hydrocarbons removed prior to use as a consumer fuel—as well as carbon dioxide, nitrogen, helium and hydrogen sulfide.^After the natural gas is extracted, it is treated at gas plants to remove impurities such as hydrogen sulfide, helium, carbon dioxide, hydrocarbons, and moisture.

^Weather, the economy, international events, production and the transportation costs -Natural gas forms over time from most organic materials -Canada is the third largest producer of natural gas in the world behind Russia and the United States .

.The world's largest gas field is Qatar's offshore North Field, estimated to have 25 trillion cubic metres[3] (9.0 × 1014 cu ft) of gas in place—enough to last more than 200 years at optimum production levels.^After years of volatile gas prices, and last...

.Connected to Qatar's North Field, it has estimated reserves of 8 to 14 trillion cubic metres[4](2.8 × 1014 to 5.0 × 1014 cu ft) of gas.^The world's largest gas field is the offshore North Field in Qatar, estimated to have 25 × 10 9 cubic metres of gas in place.

^According to a 2008 report released by Navigant Consulting, paid for by a foundation allied with the gas industry, there could be as much as 842 trillion cubic feet of retrievable gas in shale fields around the country.

.Because natural gas is not a pure product, when non-associated gas is extracted from a field under supercritical (pressure/temperature) conditions, it may partially condense upon isothermic depressurizing—an effect called retrograde condensation.^Natural Gas What effects Natural Gas prices?

.One method to deal with this problem is to reinject dried gas free of condensate to maintain the underground pressure and to allow reevaporation and extraction of condensates.^One method of mitigating this problem is to reinject dried gas, free of condensate, to maintain the underground pressure and to allow re-evaporation and extraction of the condensate.

Town gas

.Town gas is a mixture of methane and other gases, mainly the highly toxic carbon monoxide, that can be used in a similar way to natural gas and can be produced by treating coal chemically.^Investing in Natural Gas: How it was used .

.This is a historic technology, still used as 'best solution' in some local circumstances, although coal gasification is not usually economic at current gas prices.^This is a historic technology, still used as 'best solution' in some local circumstances, although coal gasification is not usually economic at current gas prices, depending upon infrastructure considerations.

.However, depending upon infrastructure considerations, it remains a future possibility.^This is a historic technology, still used as 'best solution' in some local circumstances, although coal gasification is not usually economic at current gas prices, depending upon infrastructure considerations.

.Most town "gashouses" located in the eastern United States in the late nineteenth and early twentieth centuries were simple by-product coke ovens which heated bituminous coal in air-tight chambers.^Coal gas (sometimes called town gas too) - made in coking ovens.

.The gas driven off from the coal was collected and distributed through town-wide networks of pipes to residences and other buildings where it was used for cooking and lighting purposes.^Supporting applications for turbines used in power generation, pipeline compression, vapor recovery, LNG boil-off, CO2 injection, and process gas.

^At Sable Island, water is removed from the gas on off shore platforms before the gas goes via pipes to Goldboro , a small town that was once the scene of a gold rush and now hopes to profit from an energy boom.

) .The coal tar that collected in the bottoms of the gashouse ovens was often used for roofing and other water-proofing purposes, and also, when mixed with sand and gravel, was used for creating bitumen for the surfacing of local streets.^Domestic use Natural gas is supplied to homes, where it is used for such purposes as cooking in natural gas-powered ranges and/or ovens, natural gas-heated clothes dryers , heating / cooling and central heating .

^Residential/Business Use Natural gas is supplied to homes, where it is used for such purposes as cooking in natural gas-powered ranges and/or ovens, natural gas-heated clothes dryers, heating/cooling and central heating .

Biogas

.When methane-rich gases are produced by the anaerobic decay of non-fossil organic matter (biomass), these are referred to as biogas (or natural biogas).^Methane gas is naturally produced whenever organic matter decays.

^However, a variety of alternative sources are being explored including the capture of methane as waste gas from landfill sites, and from methane hydrates which are methane hydrocarbons surrounded by a lattice of ice.

.Methanogenic archaea are responsible for all biological sources of methane, some in symbiotic relationships with other life forms, including termites, ruminants, and cultivated crops.^Methanogenic archaea are responsible for all biological sources of methane, some in symbiotic relationships with other life forms, including termites, ruminants, and cultivated crops.

^Pakistan and Iran have resolved almost all other issues pertaining to the gas pipeline project, including pricing of gas, project details and quantity of gas to be purchased, Dawn newspaper quoted unnamed sources as saying.

.Methane released directly into the atmosphere would be considered a pollutant, however, methane in the atmosphere is oxidised, producing carbon dioxide and water.^When it is burned it releases carbon dioxide (CO2), water (2H2O) and energy.

.Methane in the atmosphere has a half life of seven years, meaning that every seven years, half of the methane present is converted to carbon dioxide and water.^When heating systems are properly adjusted, the by-product of combustion is water vapor and carbon dioxide -- the same things we exhale as we breathe.

.Landfill gas is a type of biogas, but biogas usually refers to gas produced from organic material that has not been mixed with other waste.^Landfill gas is a type of biogas, but biogas usually refers to gas produced from organic material that has not been mixed with other waste.

.If the gas is not removed, the pressure may get so high that it works its way to the surface, causing damage to the landfill structure, unpleasant odor, vegetation die-off and an explosion hazard.^If the gas is not removed, the pressure may get so high that it works its way to the surface, causing damage to the landfill structure, unpleasant odor, vegetation die-off and an explosion hazard.

^El Paso Natural Gas Company on August 30 said it would have to take a portion of its pipeline out of service immediately because of damage to the pipeline from a third-party working in its right-of-way in Arizona.

^Producers who cannot sell or store their gas will have limited options: cap their wells, which could be bad for them in the long term; give gas away for free, which has happened before when producers did not want to halt production; or flare it  burn it off into the atmosphere.

^Some kind of part share of the property, so that it is part rented by the former morgagee, is also likely in the UK. The whole legislative and social security system in the UK is different to the States.

.There are usually trace amounts of hydrogen sulfide and siloxanes, but their concentration varies widely.^There are usually trace amounts of hydrogen sulfide and siloxanes, but their concentration varies widely.

.It is usually more economical to combust the gas on site or within a short distance of the landfill using a dedicated pipeline.^It is usually more economical to combust the gas on site or within a short distance of the landfill using a dedicated pipeline.

^This is a historic technology, still used as 'best solution' in some local circumstances, although coal gasification is not usually economic at current gas prices, depending upon infrastructure considerations.

^Other components—such as water vapor, carbon dioxide, and nitrogen—may be removed to improve the quality of the natural gas or to make it easier to move the gas over great distances through pipelines.

^Regardless of the source, most raw natural gas contains dirt, sand, and water vapor, which must be removed before further processing to prevent contamination and corrosion of the equipment and pipelines.

.If low temperatures condense water out of the gas, siloxanes can be lowered as well because they tend to condense out with the water vapor.^Cutbacks in the production of petrochemicals, plastics, wood products, metals, motor vehicles and fertilizers, as well as lower gas demand for industrial boilers, are primarily responsible for the decline.

.Other non-methane components may also be removed in order to meet emission standards, to prevent fouling of the equipment or for environmental considerations.^Other non-methane components may also be removed in order to meet emissions standards, to prevent fouling of the equipment or for environmental considerations.

.Biogas is usually produced using agricultural waste materials, such as otherwise unusable parts of plants and manure.^Biogas is usually produced using agricultural waste materials, such as otherwise unusable parts of plants and manure.

.Biogas can also be produced by separating organic materials from waste that otherwise goes to landfills.^Landfill gas is a type of biogas, but biogas usually refers to gas produced from organic material that has not been mixed with other waste.

.Using materials that would otherwise generate no income, or even cost money to get rid of, improves the profitability and energy balance of biogas production.^Using materials that would otherwise generate no income, or even cost money to get rid of, improves the profitability and energy balance of biogas production.

^Even so, according to the President, "commercialization of fusion has the potential to dramatically improve America's energy security while significantly reducing air pollution and emissions of greenhouse gases."

.Anaerobic lagoons produce biogas from manure, while biogas reactors can be used for manure or plant parts.^Anaerobic lagoons are used to produce biogas from manure, while biogas reactors can be used for manure or plant parts.

.Like landfill gas, biogas is mostly methane and carbon dioxide, with small amounts of nitrogen, oxygen and hydrogen.^It is made up of carbon, hydrogen, oxygen, nitrogen and varying amounts of sulphur.

Crystallized natural gas - Hydrates

.Huge quantities of natural gas (primarily methane) exist in the form of hydrates under sediment on offshore continental shelves and on land in arctic regions that experience permafrost such as those in Siberia (hydrates require a combination of high pressure and low temperature to form).^Natural gas is continental .

.Particularly high efficiencies can be achieved through combining gas turbines with a steam turbine in combined cycle mode.^Particularly high efficiencies can be achieved through combining gas turbines with a steam turbine in combined cycle mode.

^These “combined-cycle” plants are much more efficient than steam units or gas turbines alone, and can achieve thermal efficiencies of up to 50 to 60 percent compared to 33 to 35 percent efficiency from traditional steam generation units that burn coal or other fossil fuels (including natural gas).

.Natural gas burns more cleanly than other fossil fuels, such as oil and coal, and produces less carbon dioxide per unit energy released.^Natural gas is still a fossil fuel, and when burned it does produce greenhouse gases.

.For an equivalent amount of heat, burning natural gas produces about 30% less carbon dioxide than burning petroleum and about 45% less than burning coal.^Both help pollute the world, but natural gas is much cleaner - per unit of energy its combustion produces 30% less carbon dioxide than oil, and about 45% less carbon dioxide than coal .

[13].Combined cycle power generation using natural gas is thus the cleanest source of power available using fossil fuels, and this technology is widely used wherever gas can be obtained at a reasonable cost.^Why use natural gas to power your generator?

.CNG is used in rural homes without connections to piped-in public utility services, or with portable grills.^CNG is used in rural homes without connections to piped-in public utility services, or with portable grills.

.However, due to CNG being less economical than LPG, LPG (propane) is the dominant source of rural gas.^However, due to CNG being less economical than LPG which is liquified propane, butane or a mixture of both, LPG is the dominant source of rural gas.

^Ormen Lange gas field's reserves in the Norwegian Sea could be 25% less than previously estimated, Norwegian business daily Dagens Naeringsliv wrote in an article published on Friday, which quotes industry sources.

.As of 2008 there were 9.6 million natural gas vehicles worldwide, led by Pakistan (2.0 million), Argentina (1.7 million), Brazil (1.6 million), Iran (1.0 million), and India (650 thousand).^Pakistan has only 21.6 Tcf of natural gas reserves, resulting in the production of 0.7 Tcf of natural gas, which is exactly the same as the level of natural gas consumption in the country.

^AT&T expects to spend an estimated $350 million to purchase about 8,000 Compressed Natural Gas (CNG) vehicles and approximately $215 million to begin replacing its passenger cars with alternative-fuel models, beginning with hybrids.

[14][15].The energy efficiency is generally equal to that of gasoline engines, but lower compared with modern diesel engines.^The energy efficiency is generally equal to that of gasoline engines, but lower compared with modern diesel engines.

.Gasoline/petrol vehicles converted to run on natural gas suffer because of the low compression ratio of their engines, resulting in a cropping of delivered power while running on natural gas (10%-15%).^Gasoline/petrol vehicles converted to run on natural gas suffer because of the low compression ratio of their engines, resulting in a cropping of delivered power while running on natural gas (10%-15%).

Aviation

.Russian aircraft manufacturer Tupolev is currently running a development program to produce LNG- and hydrogen-powered aircraft.^Aviation Russian aircraft manufacturer Tupolev is currently running a development program to produce LNG- and hydrogen-powered aircraft.

[17].The program has been running since the mid-1970s, and seeks to develop LNG and hydrogen variants of the Tu-204 and Tu-334 passenger aircraft, and also the Tu-330 cargo aircraft.^The program has been running since the mid-1970s, and seeks to develop LNG and hydrogen variants of the Tu-204 and Tu-334 passenger aircraft, and also the Tu-330 cargo aircraft.

.It claims that at current market prices, an LNG-powered aircraft would cost 5,000 roubles (~ $218/ £112) less to operate per ton, roughly equivalent to 60%, with considerable reductions to carbon monoxide, hydrocarbon and nitrogen oxide emissions.^The cost to move and process LNG is much higher than the current price of gas, so if those plants (which are mostly idle at the moment) actually bring in LNG, they are doing so at a significant loss simply to generate cash flow.

.The advantages of liquid methane as a jet engine fuel are that it has more specific energy than the standard kerosene mixes do and that its low temperature can help cool the air which the engine compresses for greater volumetric efficiency, in effect replacing an intercooler.^The advantages of liquid methane as a jet engine fuel are that it has more specific energy than the standard kerosene mixes and that its low temperature can help cool the air which the engine compresses for greater volumetric efficiency, in effect replacing an intercooler .

.Hydrogen has various applications: it is a primary feedstock for the chemical industry, a hydrogenating agent, an important commodity for oil refineries, and a fuel source in hydrogen vehicles.^It is an important fuel source and a major feedstock for producing ammonia , hydrogen , petrochemicals and fertilizers .

.Many existing pipelines in North America are close to reaching their capacity, prompting some politicians representing colder areas to speak publicly of potential shortages.^Many existing pipelines in North America are close to reaching their capacity, prompting some politicians in colder climates to speak publicly of potential shortages.

.In Europe, the gas pipeline network is already dense in the West[18].^Because of its repeated conflicts with Ukraine and others, Russia wants to build a completely new set of natural gas pipelines to supply Europe.

The Oil and The Glory by Steve LeVine6 January 2010 8:12 UTCoilandglory.com [Source type: FILTERED WITH BAYES]

^The Middle East/North Africa region also has a developed network (PDF) of pipelines, primarily leading into southern Europe.

^Now, Vladimir Putin intends to build on Russia's restored power by erecting two gigantic new natural gas pipelines into Europe, which already relies on Russia for almost a third of its gas.

The Oil and The Glory by Steve LeVine6 January 2010 8:12 UTCoilandglory.com [Source type: FILTERED WITH BAYES]

.New pipelines are planned or under construction in Eastern Europe and between gas fields in Russia, Near East and Northern Africa and Western Europe.^The largest two natural gas fields are probably South Pars Gas Field in Iran and Urengoy gas field in Russia, with reserves on the order of 1013 m³.

.Sea transport using CNG carrier ships that are now under development may be competitive with LNG transport in specific conditions.^Sea transport using CNG carrier ships that are now under development may be competitive with LNG transport in specific conditions.

.For LNG transport a liquefaction plant is needed at the exporting end and regasification equipment at the receiving terminal.^For LNG transportation by seagoing tankers, an LNG liquefaction plant is needed at the exporting end and an LNG regasification plant is needed at the receiving LNG terminal .

Shipborne regasification equipment is also practicable. .LNG transportation is established as the preferred technology for long distance, high volume transportation of natural gas, whereas pipeline transport is preferred for transport for distances up to typically 4.000 km overland and approximately half that distance over seas.^Transportation A natural gas processing plant.

^The major means of transporting large volumes of natural gas overland is by pipelines and pipelines have been established as the preferred transportation mode for overland distances of up to about 4,000 kilometres (2,500 miles).

.For CNG transport high pressure, typically above 200 bars, is used.^Compression Increasing the pressure of natural gas to allow it to be transported by pipeline Compressor A machine used to boost natural gas pressure to move it through pipelines or other facilities.

.Compressors and decompression equipment are less capital intensive and may be economical in smaller unit sizes than liquefaction/regasification plants.^For LNG transportation by seagoing tankers, an LNG liquefaction plant is needed at the exporting end and an LNG regasification plant is needed at the receiving LNG terminal .

.Natural gas trucks and carriers may transport natural gas directly to end-users, or to distribution points such as pipelines for further transport.^They may transport natural gas directly to end-users, or to distribution points such as pipelines for further transport.

In the foreground (left) is one of numerous wells for the underground storage area, with an LNG plant and above ground storage tanks in the background (right).

.In the past, the natural gas which was recovered in the course of recovering petroleum could not be profitably sold, and was simply burned at the oil field (known as flaring).^Provider of oil/natural gas services.

.Additionally, companies now recognize that value for the gas may be achieved with LNG, CNG, or other transportation methods to end-users in the future.^Additionally, companies now recognize that value for the gas may be achieved with LNG, CNG, or other transportation methods to end-users in the future.

^Fracturing (or fracing) A reservoir stimulation technique in which fluids are pumped into a potentially productive formation under high pressure to create or enlarge fractures which allows the oil or gas to flow from the zone at higher rates.

.Similarly, some landfills that also discharge methane gases have been set up to capture the methane and generate electricity.^Similarly, some landfills that also discharge methane gases have been set up to capture the methane and generate electricity.

^Natural gas is increasingly used at newer “peaker” power plants (such as the Emery Generating Station near Mason City, Iowa) that generate extra electricity during periods of peak demand during summer heat waves.

.Storage near the ultimate end-users helps to best meet volatile demands, but this may not always be practicable.^Storage near the ultimate end-users helps to best meet volatile demands, but this may not always be practicable.

.With 15 nations accounting for 84% of the worldwide production, access to natural gas has become a significant factor in international economics and politics.^Natural Gas is also the feedstock for hydrogen production.

In this respect, control over the pipelines is a major strategic factor.[22].In particular, in the 2000s, Gazprom, the Russian national energy company, has engaged in disputes with Ukraine and Belarus over the price of its natural gas, which have created worries that gas deliveries to parts of Europe could be cut off for political reasons.^What causes natural gas prices to rise?

Environmental effects

Climate change

.Natural gas is often described as the cleanest fossil fuel, producing less carbon dioxide per joule delivered than either coal or oil.^Both help pollute the world, but natural gas is much cleaner - per unit of energy its combustion produces 30% less carbon dioxide than oil, and about 45% less carbon dioxide than coal .

[13], and far fewer pollutants than other fossil fuels. .However, in absolute terms it does contribute substantially to global carbon emissions, and this contribution is projected to grow.^However, it does contribute significantly to global carbon dioxide emissions.

.According to the IPCC Fourth Assessment Report (Working Group III Report, Chapter 4), in 2004 natural gas produced about 5,300 Mt/yr of CO2 emissions, while coal and oil produced 10,600 and 10,200 respectively (Figure 4.4); but by 2030, according to an updated version of the SRES B2 emissions scenario, natural gas would be the source of 11,000 Mt/yr, with coal and oil now 8,400 and 17,200 respectively.^Provider of oil/natural gas services.

[24].(Total global emissions for 2004 were estimated at over 27,200 Mt.^According to the IPCC Fourth Assessment Report , in 2004 natural gas produced about 5,300 M t /year of carbon dioxide emissions, while coal and oil produced 10,600 and 10,200 Mt/yr respectively.

.In addition, natural gas itself is a greenhouse gas (methane) far more potent than carbon dioxide when released into the atmosphere, although released in much smaller quantities.^NGVs can also reduce emissions of carbon dioxide, the primary greenhouse gas.

.Natural gas is mainly composed of methane, which has a radiative forcing twenty times greater than carbon dioxide.^Before raw natural gas extracted from those reservoirs can be used as a fuel, it must undergo extensive processing to remove almost all materials other than methane.

^For instance: Countries trying to meet the greenhouse emissions limits set by the Kyoto Protocol are rapidly building natural gas-fired power plants, which emit much less carbon dioxide than do coal plants.

.This means a ton of methane in the atmosphere traps in as much radiation as 20 tons of carbon dioxide.^It’s because, in addition to carbon dioxide reductions, NGVs also emit less carbon monoxide, non-methane organic gas and nitrogen oxides.

.Carbon dioxide still receives the lion's share of attention over greenhouse gases because it is released in much larger amounts.^Carbon dioxide receives the most attention over greenhouse gases because it is in much higher concentrations.

^For instance: Countries trying to meet the greenhouse emissions limits set by the Kyoto Protocol are rapidly building natural gas-fired power plants, which emit much less carbon dioxide than do coal plants.

.Current USEPA estimates place global emissions of methane at 3 trillion cubic feet annually[25], or 3.2% of global production[26].^Qatar also has 25 trillion cubic meters of natural gas (14% of the world's proven supply)[13], enough to last 250 years at current production levels.

.Direct emissions of methane represented 14.3% of all global anthropogenic greenhouse gas emissions in 2004 [27].^In 2006, Texas produced more than 5.1 trillion cubic feet or 27.8 percent of all natural gas produced in the U.S., still more than any other state ( Exhibit 5-6 ).

Other pollutants

.Natural gas produces far lower amounts of sulfur dioxide and nitrous oxides than any other fossil fuel.^Biomethane is the "natural, natural gas" and is far better for the environment and the economy than natural gas.

Safety

A pipeline odorant injection station

.In any form, a minute amount of odorant such as t-butyl mercaptan, with a rotting-cabbage-like smell, is added to the otherwise colorless and almost odorless gas, so that leaks can be detected before a fire or explosion occurs.^Since it is also very flammable, it is important that natural gas leaks be detected before a fire or explosion occurs.

^In any form, a minute amount of odorant such as t-butyl mercaptan, with a rotting-cabbage-like smell, is added to the otherwise colorless and odorless gas, so that leaks can be detected before a fire or explosion occurs.

.Adding odorant to natural gas began in the United States after the 1937 New London School explosion.^Odorizing of natural gas began in the United States after the 1937 New London School explosion in the town of New London, Texas .

.The buildup of gas in the school went unnoticed, killing three hundred students and faculty when it ignited.^The buildup of gas in the school went unnoticed, killing three hundred students and faculty when it ignited.

.Odorants are considered non-toxic in the extremely low concentrations occurring in natural gas delivered to the end user.^Such odorants are considered non-toxic in the extremely low concentrations at which they are used.

.In mines, where methane seeping from rock formations has no odor, sensors are used, and mining apparatuses have been specifically developed to avoid ignition sources, e.g., the Davy lamp.^In mines, where methane seeping from rock formations has no odor, sensors are used, and mining apparatuses have been specifically developed to avoid ignition sources, e.g., the Davy lamp.

^In any form, a minute amount of odorant such as t-butyl mercaptan, with a rotting-cabbage-like smell, is added to the otherwise colorless and odorless gas, so that leaks can be detected before a fire or explosion occurs.

.Individual homes, small businesses and boats are most frequently affected when an internal leak builds up gas inside the structure.^Individual homes, small businesses and boats are most frequently affected when an internal leak builds up gas inside the structure.

.Occasionally, the gas can collect in high enough quantities to cause a deadly explosion, disintegrating one or more buildings in the process.^Occasionally, the gas can collect in high enough quantities to cause a deadly explosion, disintegrating one or more buildings in the process.

.The gas usually dissipates readily outdoors, but can sometimes collect in dangerous quantities if weather conditions are right.^The gas usually dissipates readily outdoors, but can sometimes collect in dangerous quantities if weather conditions are right.

.Some gas fields yield sour gas containing hydrogen sulfide (H2S).^Such gas is referred to as coalbed gas or coalbed methane (CBM) and it is also called sweet gas because it is relatively free of hydrogen sulfide.

^During the 1990s, western companies got access to some of Russia ’s most technologically difficult-to-develop oil and natural gas fields.

The Oil and The Glory by Steve LeVine6 January 2010 8:12 UTCoilandglory.com [Source type: FILTERED WITH BAYES]

This untreated gas is toxic. .Amine gas treating, an industrial scale process which removes acidicgaseous components, is often used to remove hydrogen sulfide from natural gas.^Natural Gas is also the feedstock for hydrogen production.

.This in turn may lead to subsidence at ground level.^With the ongoing credit crisis still unfolding, an increase in imports that allows maintenance of present EU consumption levels may turn out to be a major accomplishment.

.According to the US Consumer Product Safety Commission (2008), 56% of unintentional deaths from non-fire CO poisoning were associated with engine-driven tools like gas-powered generators and lawn mowers.^In general, I happen to like natural gas.

.Natural gas heating systems accounted for 4% of these deaths.^These customers include local distribution companies, which resell the gas to residential and business customers; electric utilities that use the natural gas to generate electricity; and large industrial customers.

.The gross heat of combustion of one kg of commercial quality natural gas is around 39 megajoules (≈10.8 kWh), but this can vary by several percent.^Percent of U.S. emissions from natural gas in Texas .

^Domestic use Natural gas is supplied to homes, where it is used for such purposes as cooking in natural gas-powered ranges and/or ovens, natural gas-heated clothes dryers , heating / cooling and central heating .

.In 2007, a price of $7 per 1,000 cubic feet (28 m3) was typical in the United States.^U.S. natural gas wellhead prices were $5.80 per thousand cubic feet (Mcf) in early 2005; by October, the price had nearly doubled, to $10.33 per Mcf .

[29].The residential price varies from 50% to 300% more than the wholesale price.^But as competitive on price as gas is nationally, the average cost Floridians paid for it in 2007 was $9.24 a unit - the highest in the nation, and more than 25 percent higher than the national average ($7.31).

Each contract is for 10,000 MMBTU (gigajoules), or 10 billion BTU. Thus, if the price of gas is $10 per million BTUs on the NYMEX, the contract is worth $100,000.

United Kingdom

.Natural gas is also traded as a commodity in Europe, principally at the United Kingdom NBP and related European hubs, such as the TTF in the Netherlands.^Domestic use Natural gas is supplied to homes, where it is used for such purposes as cooking in natural gas-powered ranges and/or ovens, natural gas-heated clothes dryers , heating / cooling and central heating .

.The actual heating value when the water formed does not condense is the net heat of combustion and can be as much as 10% less.^Degree Day (Heating) - A measure of how much actual temperatures fall below a standard reference temperature.

.In the United States, retail sales are often in units of therms (th); 1 therm = 100,000 BTU. Gas meters measure the volume of gas used, and this is converted to therms by multiplying the volume by the energy content of the gas used during that period, which varies slightly over time.^One therm equals 100,000 Btus; a decatherm is equal to a million Btus.

.Wholesale transactions are generally done in decatherms (Dth), or in thousand decatherms (MDth), or in million decatherms (MMDth).^One thousand Dth, or an MDth, is roughly the energy content of a million cubic feet (MMcf) of gas volume.

.As of 2009, the Potential Gas Committee estimated that the United States has total future recoverable natural gas resources approximately 100 times greater than current annual consumption.^In total, 30 states store natural gas within their borders.

.The LNG and LPG is transported by specialized transport ships, as the gas is liquified at cryogenic temperatures.^The project involved a scheme to ship Egyptian natural gas in liquid form (LNG) to Turkey.

^PROTECTIONISM & THE NATURAL GAS INDUSTRY IN INDIA In the case of the Iran to India natural gas pipeline, India proposed the transportation of natural gas in liquid form (LNG), using the coastline along the Arabian Sea.

.The specification of each LNG/LPG cargo will usually contain the energy content, but this information is in general not available to the public.^Hydrogen could be generated by, say, using solar energy to split water molecules, but don't count that happening on a large scale as long as gas is available.

Sources

Fossil natural gas

[[File:|thumb|right|Natural gas drillingrig in Texas.]]
In the 1800s, natural gas was usually produced as a byproduct of producing oil, since the small, light gas carbon chains come out of solution as it undergoes pressure reduction from the reservoir to the surface, similar to uncapping a bottle of soda pop where the carbon dioxide effervesces. Unwanted natural gas can be a disposal problem at the well site. If there is not a market for natural gas near the wellhead it was virtually valueless since it must be piped to the end user. In the 1800s and early 1900s, such unwanted gas was usually burned off at the wellsite. Often, unwanted gas (or 'stranded' gas without a market) is pumped back into the reservoir with an 'injection' well for disposal or repressurizing the producing formation. Today, in locations with a high natural gas demand (such as the United States), pipelines are constructed to take the gas from the wellsite to the end consumer.

Another solution is to export the natural gas as a liquid.[2] Gas-to-liquid (GTL) is a developing technology that converts stranded natural gas into synthetic gasoline, diesel or jet fuel through the Fischer-Tropsch process developed in World War II Germany. Such fuel can be transported to users through conventional pipelines and tankers. Proponents claim GTL burn cleaner than comparable petroleum fuels. Most major international oil companies are in an advanced stage of GTL production, with a world-scale (140,000 barrels a day) GTL plant in Qatar scheduled to be in production before 2010.

The world's largest proven gas reserves are located in Russia, with 4.757 × 1013 m³ (1.6 × 1015 cubic feet). With the Gazprom company, Russia is also the world's largest natural gas producer. Major proven resources (in billion cubic meters) are world 175,400 (2006), Russia 47,570 (2006), Iran 26,370 (2006), Qatar 25,790 (2007), Saudi Arabia 6,568 (2006) and United Arab Emirates 5,823 (2006).
It is estimated that there are also about 900 tetrillion cubic meters of "unconventional" gas such as shale gas, of which 180 tetrillion may be recoverable.[4]

The world's largest gas field is Qatar's offshore North Field, estimated to have 25 trillion cubic meters[5] (9.0 × 1014cubic feet) of gas in place—enough to last more than 200 years at optimum production levels. The second largest natural gas field is the South Pars Gas Field in Iranian waters in the Persian Gulf. Located next to Qatar's North Field, it has an estimated reserve of 8 to 14 trillion cubic meters[6](2.8 × 1014 to 5.0 × 1014 cubic feet) of gas.

Because natural gas is not a pure product, as the reservoir pressure drops when non-associated gas is extracted from a field under supercritical (pressure/temperature) conditions, the higher molecular weight components may partially condense upon isothermic depressurizing — an effect called retrograde condensation. The liquid thus formed may get trapped as the pores of the gas reservoir get deposited. One method to deal with this problem is to re-inject dried gas free of condensate to maintain the underground pressure and to allow re-evaporation and extraction of condensates.

Town gas

Town gas is a synthetically produced mixture of methane and other gases, mainly the highly toxic carbon monoxide, that can be used in a similar way to natural gas and can be produced by treating coal chemically. This is a historic technology, still used as 'best solution' in some local circumstances, although coal gasification is not usually economic at current gas prices. However, depending upon infrastructure considerations, it remains a future possibility.

Most town "gashouses" located in the eastern United States in the late nineteenth and early twentieth centuries were simple by-product coke ovens which heated bituminous coal in air-tight chambers. The gas driven off from the coal was collected and distributed through town-wide networks of pipes to residences and other buildings where it was used for cooking and lighting purposes. (Gas heating did not come into widespread use until the last half of the twentieth century.) The coal tar that collected in the bottoms of the gashouse ovens was often used for roofing and other water-proofing purposes, and also, when mixed with sand and gravel, was used for creating bitumen for the surfacing of local streets.

Methanogenic archaea are responsible for all biological sources of methane, some in symbiotic relationships with other life forms, including termites, ruminants, and cultivated crops. Methane released directly into the atmosphere would be considered a pollutant. However, methane in the atmosphere is oxidized, producing carbon dioxide and water. Methane in the atmosphere has a half life of seven years, meaning that if a tonne of methane were emitted today, 500 kilograms would have broken down to carbon dioxide and water after seven years.

Other sources of methane, the principal component of natural gas, include landfill gas, biogas and methane hydrate. Biogas, and especially landfill gas, are already used in some areas, but their use could be greatly expanded. Landfill gas is a type of biogas, but biogas usually refers to gas produced from organic material that has not been mixed with other waste.

Landfill gas is created from the decomposition of waste in landfills. If the gas is not removed, the pressure may get so high that it works its way to the surface, causing damage to the landfill structure, unpleasant odor, vegetation die-off and an explosion hazard. The gas can be vented to the atmosphere, flared or burned to produce electricity or heat. Experimental systems were being proposed for use in parts Hertfordshire, UK and Lyon in France.

Once water vapor is removed, about half of landfill gas is methane. Almost all of the rest is carbon dioxide, but there are also small amounts of nitrogen, oxygen and hydrogen. There are usually trace amounts of hydrogen sulfide and siloxanes, but their concentration varies widely. Landfill gas cannot be distributed through utility natural gas pipelines unless it is cleaned up to less than 3% CO2, and a few parts per million H2S, because CO2 and H2S corrode the pipelines.[8] It is usually more economical to combust the gas on site or within a short distance of the landfill using a dedicated pipeline. Water vapor is often removed, even if the gas is combusted on site. If low temperatures condense water out of the gas, siloxanes can be lowered as well because they tend to condense out with the water vapor. Other non-methane components may also be removed in order to meet emission standards, to prevent fouling of the equipment or for environmental considerations. Co-firing landfill gas with natural gas improves combustion, which lowers emissions.

Gas generated in sewage treatment plants is commonly used to generate electricity. For example, the Hyperion sewage plant in Los Angeles burns 8 million cubic feet of gas per day to generate power [9] New York City utilizes gas to run equipment in the sewage plants, to generate electricity, and in boilers.[10] Using sewage gas to make electricity is not limited to large cities. The city of Bakersfield, California uses cogeneration at its sewer plants.[11] California has 242 sewage wastewater treatment plants, 74 of which have installed anaerobic digesters. The total biopower generation from the 74 plants is about 66 MW.[12]

Biogas is usually produced using agricultural waste materials, such as otherwise unusable parts of plants and manure. Biogas can also be produced by separating organic materials from waste that otherwise goes to landfills. Such method is more efficient than just capturing the landfill gas it produces. Using materials that would otherwise generate no income, or even cost money to get rid of, improves the profitability and energy balance of biogas production.

Anaerobic lagoons produce biogas from manure, while biogas reactors can be used for manure or plant parts. Like landfill gas, biogas is mostly methane and carbon dioxide, with small amounts of nitrogen, oxygen and hydrogen. However, with the exception of pesticides, there are usually lower levels of contaminants.

Crystallized natural gas - Hydrates

Huge quantities of natural gas (primarily methane) exist in the form of hydrates under sediment on offshore continental shelves and on land in arctic regions that experience permafrost such as those in Siberia (hydrates require a combination of high pressure and low temperature to form). However, as of 2010[update] no technology has been developed to produce natural gas economically from hydrates.

It costs anywhere between once and twice as much to produce usable natural gas from crystallized natural gas, using current technology.[14]

Natural gas processing

The image below is a schematic block flow diagram of a typical natural gas processing plant. It shows the various unit processes used to convert raw natural gas into sales gas pipelined to the end user markets.

Uses

Power generation

Natural gas is a major source of electricity generation through the use of gas turbines and steamturbines. Most grid peaking power plants and some off-grid engine-generators use natural gas. Particularly high efficiencies can be achieved through combining gas turbines with a steam turbine in combined cycle mode. Natural gas burns more cleanly than other fossil fuels, such as oil and coal, and produces less carbon dioxide per unit energy released. For an equivalent amount of heat, burning natural gas produces about 30% less carbon dioxide than burning petroleum and about 45% less than burning coal.[20] Combined cycle power generation using natural gas is thus the cleanest source of power available using fossil fuels, and this technology is widely used wherever gas can be obtained at a reasonable cost. Fuel cell technology may eventually provide cleaner options for converting natural gas into electricity, but as yet it is not price-competitive.

Domestic use

The examples and perspective in this article deal primarily with the United States and do not represent a worldwide view of the subject. Please improve this article and discuss the issue on the talk page.

Transportation

Compressed natural gas (methane) is a cleaner alternative to other automobile fuels such as gasoline (petrol) and diesel. As of 2008 there were 9.6 million natural gas vehicles worldwide, led by Pakistan (2.0 million), Argentina (1.7 million), Brazil (1.6 million), Iran (1.0 million), and India (650,000).[21][22] The energy efficiency is generally equal to that of gasoline engines, but lower compared with modern diesel engines. Gasoline/petrol vehicles converted to run on natural gas suffer because of the low compression ratio of their engines, resulting in a cropping of delivered power while running on natural gas (10%-15%). CNG-specific engines, however, use a higher compression ratio due to this fuel's higher octane number of 120–130.[23]

Fertilizers

Aviation

Russian aircraft manufacturer Tupolev is currently running a development program to produce LNG- and hydrogen-powered aircraft.[24] The program has been running since the mid-1970s, and seeks to develop LNG and hydrogen variants of the Tu-204 and Tu-334 passenger aircraft, and also the Tu-330 cargo aircraft. It claims that at current market prices, an LNG-powered aircraft would cost 5,000 roubles (~ $218/ £112) less to operate per ton, roughly equivalent to 60%, with considerable reductions to carbon monoxide, hydrocarbon and nitrogen oxide emissions.

The advantages of liquid methane as a jet engine fuel are that it has more specific energy than the standard kerosene mixes do and that its low temperature can help cool the air which the engine compresses for greater volumetric efficiency, in effect replacing an intercooler. Alternatively, it can be used to lower the temperature of the exhaust.

Hydrogen

Natural gas can be used to produce hydrogen, with one common method being the hydrogen reformer. Hydrogen has various applications: it is a primary feedstock for the chemical industry, a hydrogenating agent, an important commodity for oil refineries, and a fuel source in hydrogen vehicles.

Gas is turned into liquid at a liquefaction plant, and is returned to gas form at regasification plant at the terminal. Shipborne regasification equipment is also used. LNG is the preferred form for long distance, high volume transportation of natural gas, whereas pipeline is preferred for transport for distances up to 4,000 km over land and approximately half that distance offshore.

CNG is transported at high pressure, typically above 200 bars. Compressors and decompression equipment are less capital intensive and may be economical in smaller unit sizes than liquefaction/regasification plants. Natural gas trucks and carriers may transport natural gas directly to end-users, or to distribution points such as pipelines.

Manlove Field natural gas storage area in Newcomb Township, Champaign County, Illinois. In the foreground (left) is one of the numerous wells for the underground storage area, with an LNG plant, and above ground storage tanks is in the background (right).]]

In the past, the natural gas which was recovered in the course of recovering petroleum could not be profitably sold, and was simply burned at the oil field in a process known as flaring. Flaring is now illegal in many countries.[26] Additionally, companies now recognize that gas may be sold to consumers in the form of LNG or CNG, or through other transportation methods. The gas is now re-injected into the formation for later recovery. The re-injection also assists oil pumping by keeping underground pressures higher.

A "master gas system" was invented in Saudi Arabia in the late 1970s, ending any necessity for flaring. Satellite observation, however, shows that flaring[27] and venting[28] are still practiced in some gas-producing countries.

Natural gas is used to generate electricity and heat for desalination. Similarly, some landfills that also discharge methane gases have been set up to capture the methane and generate electricity.

Natural gas is often stored underground inside depleted gas reservoirs from previous gas wells, salt domes, or in tanks as liquefied natural gas. The gas is injected in a time of low demand and extracted when demand picks up. Storage nearby end users helps to meet volatile demands, but such storage may not always be practicable.

With 15 countries accounting for 84% of the worldwide production, access to natural gas has become an important issue in international politics, and countries vie for control of pipelines.[29] In the 2000s, Gazprom, the state-owned energy company in Russia, engaged in disputes with Ukraine and Belarus over the price of natural gas, which have created worries that gas deliveries to parts of Europe could be cut off for political reasons.[30]

Environmental effects

CO2 emissions

Natural gas is often described as the cleanest fossil fuel, producing less carbon dioxide per joule delivered than either coal or oil[20] and far fewer pollutants than other fossil fuels. However, in absolute terms, it does contribute substantially to global carbon emissions, and this contribution is projected to grow. According to the IPCC Fourth Assessment Report (Working Group III Report, chapter 4), in 2004, natural gas produced about 5.3 billion tons a year of CO2 emissions, while coal and oil produced 10.6 and 10.2 billion tons respectively (figure 4.4). According to an updated version of the SRES B2 emissions scenario, however, by the year 2030, natural gas would be the source of 11 billion tons a year, with coal and oil now 8.4 and 17.2 billion respectively because demand is increasing 1.9% a year[31] (Total global emissions for 2004 were estimated at over 27,200 million tons).

In addition, natural gas itself is a greenhouse gas more potent than carbon dioxide when released into the atmosphere, although natural gas is released in much smaller quantities. However, methane is oxidized in the atmosphere, and hence natural gas has a residence lifetime in the atmosphere for approximately 12 years, compared to CO2, which is already oxidized, and has an effect for 100 to 500 years. Natural gas is mainly composed of methane, which has a radiative forcing twenty times greater than carbon dioxide. Based on such composition, a ton of methane in the atmosphere traps in as much radiation as 20 tons of carbon dioxide, but remains in the atmosphere for a 8-40 times shorter time. Carbon dioxide still receives the lion's share of attention over greenhouse gases because it is released in much larger amounts. Still, it is inevitable when natural gas is used on a large scale that some of it will leak into the atmosphere. Current estimates by the EPA place global emissions of methane at 3 trillion cubic feet annually,[32] or 3.2% of global production.[33] Direct emissions of methane represented 14.3% of all global anthropogenic greenhouse gas emissions in 2004.[34]

Safety

In any form, a minute amount of odorant such as t-butyl mercaptan, with a rotting-cabbage-like
smell, is added to the otherwise colorless and almost odorless gas, so that leaks can be detected before a fire or explosion occurs. Sometimes a related compound, thiophane is used, with a rotten-egg smell. Adding odorant to natural gas began in the United States after the 1937 New London School explosion. The buildup of gas in the school went unnoticed, killing three hundred students and faculty when it ignited. Odorants are considered non-toxic in the extremely low concentrations occurring in natural gas delivered to the end user.

In mines, where methane seeping from rock formations has no odor, sensors are used, and mining apparatuses have been specifically developed to avoid ignition sources such as the Davy lamp.

Explosions caused by natural gas leaks occur a few times each year. Individual homes, small businesses and boats are most frequently affected when an internal leak builds up gas inside the structure. Frequently, the blast will be enough to significantly damage a building but leave it standing. In these cases, the people inside tend to have minor to moderate injuries. Occasionally, the gas can collect in high enough quantities to cause a deadly explosion, disintegrating one or more buildings in the process. The gas usually dissipates readily outdoors, but can sometimes collect in dangerous quantities if weather conditions are right. However, considering the tens of millions of structures that use the fuel, the individual risk of using natural gas is very low.

Extraction of natural gas (or oil) leads to decrease in pressure in the reservoir. Such decrease in pressure in turn may result in subsidence at ground level. Subsidence may affect ecosystems, waterways, sewer and water supply systems, foundations, and so on.

Natural gas heating systems are a minor source of carbon monoxide deaths in the United States. According to the US Consumer Product Safety Commission (2008), 56% of unintentional deaths from non-fire CO poisoning were associated with engine-driven tools like gas-powered generators and lawn mowers. Natural gas heating systems accounted for 4% of these deaths. Improvements in natural gas furnace designs have greatly reduced CO poisoning concerns. Detectors are also available that warn of carbon monoxide and/or explosive gas (methane, propane, etc.).

Releasing the gas is accomplished by hydrofracking. To force the natural gas out of the shale, drillers force one to nine million gallons of fresh water through the driven pipe into the shale. The high pressure water breaks up or "fracks" the shale that, in turn, releases the trapped gas. Sand is added to the water as a propellant to keep the fractures in the shale open and to enable the gas to flow up the pipe to the surface. A variety of chemicals are also added to the fresh water to keep the well pipe clean and the gas flowing easily. These chemicals include lubricants to reduce friction, biocides to eliminate fouling, scale inhibitors, oxygen scavengers to reduce oxygen in the borehole, and acids to clean the perforations in the pipe.

Dealing with fracking fluid can be a challenge. Along with the gas, 30% to 70% of the chemically-laced frack fluid, or flow back, rises to the surface. Additionally, a significant amount of salt and other minerals, once a part of the rock layers that were under prehistoric seas, are added to the mix as they dissolve in the frack fluid.

The price of natural gas varies greatly depending on location and type of consumer. In 2007, a price of $7 per 1,000 cubic feet (28 m3) was typical in the United States. The typical caloric value of natural gas is roughly 1,000 British thermal units (BTU) per cubic foot, depending on gas composition. This corresponds to around $7 per million BTU, or around $7 per gigajoule. In April 2008, the wholesale price was $10 per 1,000 cubic feet (28 m3) ($10/MMBTU).[38] The residential price varies from 50% to 300% more than the wholesale price. At the end of 2007, this was $12–$16 per 1,000 cu ft (28 m3).[39] Natural gas in the United States is traded as a futures contract on the New York Mercantile Exchange. Each contract is for 10,000 MMBTU (~10,550 gigajoules), or 10 billion BTU. Thus, if the price of gas is $10 per million BTUs on the NYMEX, the contract is worth $100,000.

United Kingdom

Natural gas is also traded as a commodity in Europe, principally at the United Kingdom NBP and related European hubs, such as the TTF in the Netherlands.

European Union

As one of the world's largest importers of natural gas, the EU is a major player on the international gas market. With Norway being one of the world's largest suppliers of natural gas as part of the extended European Economic Area, most discussions can be conducted within the EU. The main supplier is then expected to be the current number two: the Russian Federation.

Gas prices for end users vary greatly across the EU.[40]. A single European energy market, one of the key objectives of the European Union, should level the prices of gas in all EU member states.

In the United States, retail sales are often in units of therms (th); 1 therm = 100,000 BTU. Gas meters measure the volume of gas used, and this is converted to therms by multiplying the volume by the energy content of the gas used during that period, which varies slightly over time. Wholesale transactions are generally done in decatherms (Dth), or in thousand decatherms (MDth), or in million decatherms (MMDth). A million decatherms is roughly a billion cubic feet of natural gas.

As of 2009, the Potential Gas Committee estimated that the United States has total future recoverable natural gas resources approximately 100 times greater than current annual consumption.[42]

Elsewhere

In the rest of the world, LNG (liquified natural gas) and LPG (liquified petroleum gas) is traded in metric tons or mmBTU as spot deliveries. Long term contracts are signed in metric tons. The LNG and LPG is transported by specialized transport ships, as the gas is liquified at cryogenic temperatures. The specification of each LNG/LPG cargo will usually contain the energy content, but this information is in general not available to the public.